Coreless type linear motor

ABSTRACT

The present invention is a linear motor comprising an improved heat dissipation mechanism, which has the function of increasing area of heat dissipation of coils of the linear motor, reducing the weight of the rotor of the motor and simplifying the heat dissipation mechanism. The coils of the present invention are not winding type and to use the center which don&#39;t have winded wires to serve as heat dissipation holes. Heat sink compound is smeared around the heat holes to increase the area of heat dissipation, and reduce the weight of the rotor such that the thrust and operating period of the motor are arisen. Besides, the present invention also can make a heat dissipation mechanism (such as a heat pipe or a air blowing pipe) be set into the heat holes to press near to heat resource and rise heat dissipation efficacy. (FIG.  1 )

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] Linear Motors can be classified into two types, core and corelesstype, according to if the rotor has a core or not. The present inventionrelates to a coreless type linear motor, especially about the one havingbetter heat dissipation effect.

[0003] 2. Description of the Prior Art

[0004] Rotors of commonly know linear motors are mainly composed ofcoils and epoxy resin; the front is used to provide the rotor with avariable magnetic field while the last is used to fasten coils. Whenelectric current passes coils of the rotor, a magnetic field is producedand interworks with the magnetic field of the permanent magnet togenerate thrust. The Manufacturing process of the rotor is to place thecoils made of copper wires into the body of the plate-type rotor, andthen to use epoxy resin and or other kinds of resin to fill and wraparound the whole coils to increase the strength of the rotor of themotor. Because quite part of energy due to electromagnetic interworkingare transformed into heat energy, the temperature of the coil raisessuch that the electric resistance of the coils rises. In this way, theelectric current value of the coils is lower down to decrease theefficacy of the rotor such that the maximum push thrust is restricted.In addition, variation of temperature also results in some problems,such as expansion and shrink of material, such that the assembly of theparts is too tight or too loose.

[0005] Commonly known methods for heat dissipation are classified intotwo following kinds: one is to set a coolant pipe into the rotor, andthe other is to use the compressed air to carry heat of the rotorsurface away (as U.S. Pat. No. 5,703,418). Both methods described abovehave obvious disadvantages: the former requires to set the coolant pipeinto the limited room of the rotor, so the mechanism is morecomplicated, the manufacturing cost is higher, the volume and weight ofthe rotor are added, and an extra mechanism is essential to guide theflow of liquid for heat dissipation such that it is not economic; thelast method is to use the compressed air to cool the surface of therotor, and comparing with the former method, it is simpler in mechanism,but worse in the effect of heat dissipation due to that the heatconductivity of the closed structure used for wrapping coils is poor tomake temperature difference between the surface of the rotor and thenearby area of the coils large.

[0006] Therefore, the methods for heat dissipation are a big problem fordesigning a linear motor.

SUMMARY OF THE INVENTION

[0007] The purpose of the present invention is to solve thedisadvantages, such as poor heat dissipation ability, complicated heatdissipation mechanism and high manufacturing cost, of the coreless typelinear motor using common known technologies described above. Besides,the present invention also avoids the condition that the assembly ofparts is too tight or too loose, or the efficacy of the motor lowers dueto raise of temperature after the linear motor is used for a period.

[0008] The consideration for the method of heat dissipation in thepresent invention is first to avoid using a coolant pipe to avoid havingmany pipes in the rotor of the linear motor and adding many complicatedmechanisms to make the coolant flow. Then, for enhancing the effect ofheat dissipation, the heat resistance of the heat source and theexternal requires to be lowered. In order to achieve the requirement,the coils of the rotor are not designed as winding type to gather thewinded coils. Although this may increase the volume slightly, heatgeneration is more centered such that it is easy and convenient to makethe heat dissipate to the air by trenching some holes at the center ofthe coils or the area around the coils to make the holes interlink toexternal air. The method not only adds the contact area between thecoils of the rotor of the motor and air, but also adds the effect ofheat dissipation of coils due to avoiding that the insulating substanceisolates thermal conduction. Besides, the weight of the rotor is reducedand the effective thrust of the linear motor is risen due to part ofmaterial is reduced.

[0009] Because the coils of the rotor provide the motive force of thelinear motor and also suffer from counterforce, heat sink compound withgood thermal conductivity is smeared around the coils for the sake ofprotecting the coils. The heat sink compound can improve the thermalconductivity between the coils and the material around the coils. Forthe sake of further promoting the heat dissipation effect of the rotor,heat sink compound is smeared around the heat dissipation holes toenlarge the heat dissipation area. In this way, when the rotor of themotor moves, flowing air around the rotor can efficiently carry the heatof the surface of the heat sink compound away.

[0010] Some mechanisms require rotors having structure with higherstrength, so heat sink compound can be filled up the heat holes.Besides, the rotor can has better effect of heat dissipation, and havebetter structure strength. In order to promote heat dissipation effectbetween the heat sink compound and air, ragged strips are set at thecontacting surface between the heat sink compound and air to increaseheat dissipation effect.

[0011] In the other hand, if the heat pipe is fastened by heat sinkcompound and buried into the heat hole. One end of the heat pipe isburied near a coil while the other end is extended to the outside of theclosed structure of the coils, so heat of the coils can be conductedeasily to the outside of the closed structure of the coils via the heatpipes such that heat can be conducted to air efficiently through theheat pipes. The heat pipe is usually made of metal having good thermalconductivity to make heat can be conducted along the heat pipe. For someairtight hallow heat pipes, the interior is designed to be almost avacuum, and have very good thermal conductivity. In order to makethermal conduction effect better, the end, which is at the exterior ofthe closed structure of the coils, of the heat pipe can be connectedwith a heat sink, which are usually made of metal, and can help totransfer heat to air.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The drawings disclose an illustrative embodiment of the presentinvention which serves to exemplify the various advantages and objectshereof, and are as follows:

[0013]FIG. 1 3D partial cutaway view of one practice sample the presentinvention

[0014]FIG. 2 3D partial cutaway view of another practice sample of thepresent invention

[0015]FIG. 3 3D partial cutaway view of the practice sample of theadditional heat pipe of the present invention

DETAILED DECRIPTION OF THE PREFERRED EMBODIMENT

[0016]FIG. 1 is the 3D partial cutaway view of one practice sample thepresent invention, wherein the linear motor contains a rotor 1 and astator 2, and the stator 2 is U-type, and the rotor 1 can slide in theU-type structure. The stator 2 is composed of two guide plates 22, 23,several plates of permanent magnets 21 and a stator bottom plate 24. Theguide plates are made of ferromagnetic material, which usually is pureiron to reduce hysteresis. Several plates of permanent magnets 21 arepasted on the top surface of the guide plate 22 and the bottom surfaceof the guide plate 23. The stator bottom plate 24 is set at the middleof the guide plates 22 and 23 having permanent magnets 21 and holds themto make the whole structure as a U-shape structure. After the structureis assembled, the permanent magnet 21 is at the middle of guide plates22, 23, and neighbors with the rotor 1. The rotor 1 is made as plateform, and composed of a rotor base 15, upper cover 13, bottom cover 11,coils 12 and heat sink compound 14. Coil troughs 111 are set on thebottom cover 11, and coils 12 are placed into the coil troughs 111. Heatholes 131 are set at the upper cover 13. After the upper cover 13 andthe bottom cover 11 are assembled, heat sink compound 14 is smeared overthe heat holes 131 and the coil troughs 111 to keep the stability of thecoils 12.

[0017] In the practice sample, the heat holes 131 are set near the coils12 of the rotor 1, and the heat sink compound 14 in the heat holes 131has good thermal conduction effect, and, besides, the heat sink compound14 can contact air directly because of setting heat holes 131, so heatproduced by the coils 12 can be conducted to the surface of the rotor 1directly via the heat sink compound 14 of the heat holes 131, and thenheat is easily carried away by the flowing air as the rotor 1 is movingand not isolated by the upper cover 13 or other components of the rotor1. The structure is simple and volume is not be added such that theeconomic value is risen.

[0018] Otherwise, except for that weight of the rotor is reduced becausethat the heat holes 131 are set on the rotor 1, the heat sink compound14 is only smeared on the surface of the coil wall 121 such that theweight pf the rotor 1 is lighter than commonly known linear motors, andinertial of the rotor is reduced while effective thrust of the rotor isincreased. In the figure, heat dissipation holes 132 are set near thecoils 12 to increase heat dissipation effect of the rotor. In order toavoid reducing the strength of the rotor 1, heat sink compound can befilled into the heat dissipation holes 132. Thermal conduction effect ofheat sink compound is quietly better than epoxy resin and make the rotorhave good strength.

[0019]FIG. 2 is the 3D partial cutaway view of another practice sampleof the present invention, wherein main difference of the linear motorfrom FIG. 1 is that heat sink compound is filled into the heat holes 131of the rotor 1. The heat holes 131 filled with the heat sink compound 14increase the weight of the rotor 1, and the material cost. However,comparing with commonly known technologies, the weight of the practicesample of the rotor in FIG. 2 is not heavier than commonly knowntechnologies. Besides, the heat sink compound 14 extends to the surfaceof the upper cover 13 and the bottom cover 11, so heat dissipationeffect is much better than commonly known technologies. In addition, theheat holes 131 of the rotor is filled with the heat sink compound 14which has similar strength of the resin, so the rotor has both goodstructure strength and heat dissipation effect.

[0020]FIG. 3 is the 3D partial cutaway view of the practice sample ofthe additional heat, heat pipes 16 are set into the heat holes 131 ofthe rotor 1, and a heat sink 17 is set at another end of the heat pipes16. The heat pipes 16 serve as the media of conducting heat of the coils12 to the heat sinks 17, and increase strength of the rotor 1. The heatsink compound 14 is smeared between the coils 12 and the heat pipes 16to increase the contact area and thermal conduction efficacy between thecoils 12 and the heat pipes 16. In the practice sample of the FIG. 3,because the heat pipes 16 are close to the heating coils 12, the heatpipes 16 provide a path for heat conduction to make heat pass throughinsulating substance via the heat pipe 16 to make heat be conducted tothe heat sink 17, and the heat sink 17 can increase the speed of heatdissipating to air to increase the efficacy of heat dissipation. Becausethe heat pipes 16 are set in the heat holes 131, it is not like thecommonly know technologies that the thickness and the length of therotor 1 are be increased due to adding enforced cooling mechanism suchthat the extra weight is increased.

[0021] Many changes and modifications in the above described embodimentof the invention can, of course, be carried out without departing fromthe scope thereof. Accordingly, to promote the progress in science andthe useful arts, the invention is disclosed and is intended to belimited only by the scope of the appended claims.

What is claimed is:
 1. A first coreless type linear motor comprising afirst rotor and a first stator, wherein said first stator comprises afirst pair of parallel guide plates made of ferromagnetic material and afirst plurality of permanent magnets are pasted on every said firstguide plates; wherein said first rotor comprises a first plate and afirst plurality of coils, said first plate and said first coils keepingat a middle of said first pair of guide plates, said first permanentmagnets on said first guide plates neighboring with said first plate;wherein a first plurality of coil troughs are set on said first plate,said first coils being buried in said first coil troughs, said firstcoils being made by winding conductive wires and a first plurality ofheat holes are formed at a center of said first coils, said first heatholes connecting to outside of said first plate to make heat of saidfirst coils transmit into air through said heat holes.
 2. A secondcoreless type linear motor comprising a second rotor and a secondstator, wherein said second stator comprises a second pair of parallelguide plates made of ferromagnetic material and a second plurality ofpermanent magnets are pasted on every said second guide plates; whereinsaid second rotor comprises a second plate and a second plurality ofcoils, said second plate and said second coils keeping at a middle ofsaid second pair of guide plates, said second permanent magnets on saidsecond guide plates neighboring with said second plate; wherein a secondplurality of coil troughs are set on said second plate, said secondcoils being buried in said second coil troughs, said second coils beingmade by winding conductive wires and a second plurality heat holes areformed at a center of said second coils, a heat sink compound beingfilled into said second heat holes after said second coils are buriedinto said second coil troughs to make heat of said second coils transitinto air easily and make said second plate have good strength.
 3. Acoreless type linear motor as recited in claim 2, wherein a plurality ofheat pipes are buried into said second heat holes.
 4. A coreless typelinear motor as recited in claim 3, wherein said heat pipes areconnected to a heat sink to help dissipate heat.
 5. A coreless typelinear motor as recited in claim 2, wherein a contact surface betweensaid heat sink compound and air has a plurality of ragged strips toincrease thermal conduction effect.
 6. A coreless type linear motor asrecited in claim 1, a plurality of heat dissipation holes are set nearsaid first and second coils of said first and second plate.
 7. Acoreless type linear motor as recited in claim 6, wherein said heat sinkcompound is filling into said heat dissipation holes to increase thestrength of plates.
 8. A coreless type linear motor as recited in claim2, a plurality of heat dissipation holes are set near said first andsecond coils of said first and second plate.
 9. A coreless type linearmotor as recited in claim 8, wherein said heat sink compound is fillinginto said heat dissipation holes to increase the strength of plates. 10.A coreless type linear motor as recited in claim 1, wherein said heatsink compound is filling among conductive wires of said first and secondcoils to make heat of conductive wires of said first and second coils beconducted easily.
 11. A coreless type linear motor as recited in claim2, wherein said heat sink compound is filling among conductive wires ofsaid first and second coils to make heat of conductive wires of saidfirst and second coils be conducted easily.